Field of the Invention
The present invention relates to a numerical controller, and more particularly, to a numerical controller configured to retrieve blocks of a machining program from a machine position.
Description of the Related Art
If a tool is broken during machining using a numerical controller, the machining is interrupted so that the tool can be replaced, and thereafter, a block (e.g., a block for the interruption of the operation) in a machining program for the resumption of the operation is identified and the operation is resumed at the identified block, in some cases. Moreover, if a contaminated portion of a machined surface of a workpiece is found after the machining is performed by using the numerical controller, a block of the machining program for the machining of the machined surface may be identified so that machining conditions can be readjusted from the identified block for re-machining. Thus, in some machining using the numerical controller, a specific block of the machining program must be retrieved. In general, a program command value, tool number, sequence number and the like are used to retrieve a specific block from the machining program.
For example, Japanese Patent Application Laid-Open No. 04-033010 discloses, as a prior art for retrieving a specific block from a machining program, a method in which a tool path is drawn on a display screen in an interactive numerical controller, a mark is inserted into that point of the drawn tool path which is expected to be checked, and the block at the point to be checked is retrieved by using the mark.
If the machining program is long and there are a large number of similar tap commands or if similar machining commands exist in succession, however, there arises a problem that it takes time and labor to find out the specific block from graphics or the like of the machining program and machining path.